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Black stool (tarry stool, melena, digested blood in the stool) in Dogs

Author: Dr. med. vet. Gisa Löwe | Last modified: 17.02.2026

When to visit the vet?

Emergency see a veterinarian immediately

If the condition worsens / symptoms persist, consult a veterinarian.

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Definition of

Tarry stool, also known as melena, is a symptom in dogs characterized by black, sticky, and tar-like feces. This condition indicates the presence of digested blood in the digestive tract, originating from the upper gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. tract.

Can Occur with the Following Diseases:

Grundlagen und mögliche Ursachen

A dog’s digestive tract consists of several sections, including the stomach and small intestineThe intestine is the medical term for the gut, including the small intestine (intestinum tenue) and the large intestine (intestinum crassum). It plays a central role in the digestion and absorption of nutrients.. When Bleeding occurs in these upper sections, the blood is chemically altered by digestive processes, resulting in the characteristic black color of the stool. This change in color is due to the breakdown of hemoglobinhemoglobin is an iron-containing protein in red blood cells responsible for transporting oxygen from the lungs to the body tissues and carbon dioxide back to the lungs. in the blood, which occurs through the action of gastric acids and enzymesEnzymes are biological catalysts that accelerate specific chemical reactions in the body without being consumed. They play a crucial role in virtually all physiological processes..

There are numerous causes of melena in dogs. One of the most common is an ulcerAn ulcer is an open wound or erosion of the skin or mucous membrane that often heals poorly and can be caused by a variety of factors, including infections and chronic inflammatory conditions. in the stomach or small intestineThe intestine is the medical term for the gut, including the small intestine (intestinum tenue) and the large intestine (intestinum crassum). It plays a central role in the digestion and absorption of nutrients.. These ulcers can be caused by medications such as NSAIDsNSAID (non-steroidal anti-inflammatory drug) stands for non-steroidal anti-inflammatory drugs, a class of medications used to relieve pain, reduce inflammatory conditions, and lower fever without using steroidal agents. They are a commonly used pain reliever in veterinary medicine. (non-steroidalNon-steroidal refers to medications or substances that are not steroids and often have anti-inflammatory, analgesic, or antipyretic effects. They are used in dogs and cats to treat Pain and Inflammatory conditions. anti-inflammatory drugsAnti-inflammatory drugs are medications that reduce inflammation. They can be divided into nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids and are used in dogs and cats to reduce Inflammatory conditions and Pain.), certain infections, tumors, or chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. inflammatory conditions. Another possible cause is the ingestionIngestion refers to the intake of substances through the mouth and their delivery to the digestive tract. In dogs and cats, the ingestion of toxic substances, foreign objects, or incompatible foods can lead to health problems. of toxicToxic means "poisonous" and refers to substances that can have harmful effects on the body, including damage to organs, cells, or disruption of metabolic processes. substances that can damage the gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. tract.

Blood clotting disorders, whether hereditary or acquired through conditions such as liver disease or poisoning, can also lead to bleeding in the digestive tract. Infections with certain parasites, such as hookworms, can also cause bleeding and, consequently, tarry stool. Finally, traumaA trauma refers to a physical injury or damage caused by external force. Traumas can range from simple cuts to severe multiple injuries. to the digestive tract, such as from swallowing foreign objects, can also cause bleeding.

Typische Begleitsymptome

Pale gums: Blood loss from melena can lead to anemia, which is manifested by pale gums.
Weakness or lethargy: Dogs with significant blood loss or internal bleeding are often weak and lethargic.
Vomiting: Frequent vomiting, possibly mixed with blood, may occur together with melena.
AbdominalThe term "abdominal" refers to anything that concerns the belly or the abdomen. It is an adjectival expression used to describe the location, symptoms, or conditions that occur in the abdominal area. pain: Dogs may show signs of abdominalThe term "abdominal" refers to anything that concerns the belly or the abdomen. It is an adjectival expression used to describe the location, symptoms, or conditions that occur in the abdominal area. discomfort, such as tucking up their abdomenThe abdomen, also known as the abdominal cavity, is the part of the body located between the rib cage and the pelvis. It houses several important organs, including the stomach, liver, kidneys, intestines, and spleen. or whining when touched.
Weight loss: In chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. cases, unintended weight loss may occur.
Loss of appetite: Dogs with gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. problems often avoid eating.

Wann zum Tierarzt?

Eskalation: RED status has already been reached: especially critical in cases of weakness, pale mucous membranes, collapse, vomiting (especially "coffee grounds"), pain, or suspected /NSAID ( ) .

A visit to the veterinarian is essential if a dog shows signs of tarry stool. This is especially important if the symptom is accompanied by other concerning symptoms such as vomiting, weakness, or abdominalThe term "abdominal" refers to anything that concerns the belly or the abdomen. It is an adjectival expression used to describe the location, symptoms, or conditions that occur in the abdominal area. pain. Blood loss, even in small amounts, can quickly lead to serious health problems in dogs.

A veterinarian should also be consulted if the affected animal is already being treated for other health problems. These could worsen or be complicated by new symptoms. A veterinary examination is particularly important if the dog is taking medications that can cause gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. discomfort.

If the dog shows clear signs of pain or appears apathetic, an immediate veterinary examination is necessary. Acting quickly can be crucial to avoid serious complications.

Symptomerkennung für den Tierhalter und tierärztliches diagnostisches Vorgehen

For pet owners, the detection of tarry stool is often visual. Observe your dog’s stool for unusual changes in color and consistency. Black, sticky stool is a clear warning sign. Also, pay attention to other physical changes or behavioral abnormalities that could indicate a health problem.

The veterinarian will perform a comprehensive medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits. and physical examination. Blood tests can be performed to detect signs of anemia or infections. Imaging procedures such as X-rayX-ray is an imaging technique that uses X-rays to create images of the inside of the body. It is often used to diagnose bone fractures, lung diseases, and other conditions. or ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. can be used to assess the gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. tract. In some cases, an endoscopy may be necessary to directly inspect the inside of the stomach and intestines and take samples for biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions..

In addition, stool tests can be performed to confirm the presence of parasites or blood in the stool. Blood coagulationBlood coagulation is a process that helps stop Bleeding when a blood vessel is damaged. Platelets and certain proteins in the plasma form a blood clot that seals the wound. tests may also be necessary to assess the dog’s tendency to bleed.

Was kann der Tierhalter tun und professionelle Therapieoptionen

While waiting for the vet appointment, there are a few things you can do to ease your dog’s condition. Make sure the dog has access to fresh water to avoid dehydrationDehydration occurs when the body loses more fluid than it takes in. This can lead to a number of problems, including headaches, Dizziness, and in extreme cases, renal failure or Cardiovascular collapse., which could be worsened by blood loss. Avoid giving the dog any medication unless the vet has specifically prescribed it.

Monitor the dog closely for changes in its condition. If the symptoms worsen or new symptoms appear, inform the veterinarian immediately. Keep the dog in a calm environment to minimize stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being., as stress can worsen symptoms.

Avoid giving the dog solid food until the veterinarian has made an accurate diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients.. A temporary fasting period can help relieve the gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. tract. Once the veterinarian has assessed your dog’s condition, they will suggest an appropriate treatment, which may include a special diet or medication to control the symptoms.

Ausblick auf aktuelle Forschung

Current research is intensively investigating how diet and certain medications can influence the causes and symptoms of tarry stool in dogs. Scientists are studying the role of ulcer-inducing factors such as NSAIDsNSAID (non-steroidal anti-inflammatory drug) stands for non-steroidal anti-inflammatory drugs, a class of medications used to relieve pain, reduce inflammatory conditions, and lower fever without using steroidal agents. They are a commonly used pain reliever in veterinary medicine. (non-steroidal anti-inflammatory drugsAnti-inflammatory drugs are medications that reduce inflammation. They can be divided into nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids and are used in dogs and cats to reduce Inflammatory conditions and Pain.) and their effects on gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. health. These medications can damage the lining of the stomach, causing bleeding that leads to melena. Researchers are investigating alternative treatment approaches that are less aggressive on the stomach to reduce the risk of tarry stool.

Another research focus is on the genetic predispositionA predisposition is an innate inclination or susceptibility of an organism to certain diseases or conditions. In dogs and cats, there may be a genetic predisposition to certain conditions such as hip dysplasia or certain heart diseases. of dogs to gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. diseases that can lead to bleeding ulcers. Through genome sequencing of various dog breeds, scientists are trying to identify genetic markers that indicate a predispositionA predisposition is an innate inclination or susceptibility of an organism to certain diseases or conditions. In dogs and cats, there may be a genetic predisposition to certain conditions such as hip dysplasia or certain heart diseases. for such diseases. These findings could lead to preventive measures and targeted therapies in the long term.

In addition, the role of probiotics and prebiotic nutritional supplements is being investigated to improve gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. health in dogs. These supplements could stabilize the microbial balance in the gut and strengthen the integrity of the gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. mucosaMucosa, also called mucous membrane, refers to the moist lining of body cavities that are connected to the outside world, such as the mouth, nose, lungs, and gastrointestinal tract. It serves to protect and facilitate the absorption of nutrients., thereby reducing the risk of bleeding and thus of melena.

An innovative approach in research is the application of imaging techniques such as magnetic resonance imaging (MRI)Magnetic resonance imaging is an imaging technique that uses strong magnetic fields and radio waves to create detailed images of the inside of the body. It is used in veterinary medicine to diagnose diseases of the brain, spine, and other organs. and high-resolution ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. techniques to examine the inner layers of the gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. wall in detail. These techniques could help identify and treat sources of bleeding early on, before serious symptoms such as tarry stool occur.

The role of stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. as a factor for gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. bleeding is also being investigated. Researchers are analyzing how stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. hormones affect gastric acid production and the mucosal barrier. Insights in this area could lead to new strategies to prevent stress-related gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. problems that could lead to tarry stool.

Another area of research focuses on the development of new diagnostic tests that can identify specific biomarkers in the blood or stool to detect gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. bleeding early. These tests could be less invasiveInvasive describes medical procedures or pathogens that enter the body or penetrate tissue. In medicine, invasive procedures can range from minimally invasive techniques to open surgery. and faster than traditional methods, enabling early treatment.

Research is also investigating the use of herbal remedies and their potential effect on gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. health. Certain plant extracts may have anti-inflammatory and healing properties that help protect the mucosaMucosa, also called mucous membrane, refers to the moist lining of body cavities that are connected to the outside world, such as the mouth, nose, lungs, and gastrointestinal tract. It serves to protect and facilitate the absorption of nutrients. and minimize the risk of bleeding.

In addition, the effect of environmental factors, such as exposureExposure refers to the Contact with or subjection to certain substances, environmental factors, or pathogens. In veterinary medicine, this can include Contact with toxins, allergens, or infectious agents that can cause health problems in dogs and cats. to certain chemicals or pollutants, on the gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. health of dogs is being investigated. These studies may provide clues as to how environmental influences can contribute to the development of melena.

An interdisciplinary approach is being pursued to understand the complex interactions between diet, geneticsGenetics is the science of genes, heredity, and the variation of organisms. It studies how genetic information is passed from generation to generation and how it influences the development, appearance, and behavior of living things., lifestyle, and environment that can lead to the development of tarry stool. Such holistic studies could enable more comprehensive preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. and treatment strategies.

Finally, the role of infections, especially bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. such as Helicobacter pylori, in connection with gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. bleeding is also being explored. The findings could offer new therapeutic approaches for the treatment and preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of melena in dogs.

Häufig gestellte Fragen

What does black stool mean in dogs? Black stool, also known as tarry stool or melena, indicates digested blood in the stool. This may indicate bleeding in the upper gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. tract.
How dangerous is tarry stool in dogs? Tarry stool can be a serious symptom that indicates internal bleeding. It requires an immediate veterinary examination to identify and treat the underlying cause.
Can certain foods cause black stool? Yes, some foods or medications can darken the stool, but true tarry stool is usually sticky and has an unpleasant odor, which indicates bleeding.
How is melena diagnosed in dogs? The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. typically includes a physical examination, blood tests, stool tests, and imaging procedures such as X-ray or ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. to identify the source of the bleeding.
Can stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. cause tarry stool in dogs? Yes, stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. can indirectly lead to gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. bleeding, which can cause tarry stool, by increasing gastric acid production and weakening the mucosal barrier.
Are all dog breeds equally affected by tarry stool? No, some breeds may be genetically more susceptible to gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. diseases that lead to tarry stool. Research is trying to identify these genetic predispositions.
What treatment options are available for melena? Treatment depends on the cause of the bleeding and may include medications, dietary changes, or, in severe cases, surgical interventions.
Can melena disappear on its own? While mild cases may heal on their own, tarry stool should always be examined by a veterinarian to rule out serious health problems.
How can I prevent my dog from getting tarry stool? Regular veterinary check-ups, a balanced diet, stressStress refers to the state of an organism reacting to external stimuli or demands. In veterinary medicine, stress can have physical or psychological effects on animals, impacting their health and well-being. reduction, and avoiding stomach irritants can help reduce the risk of gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. bleeding.
What role do probiotics play in preventing tarry stool? Probiotics can support the balance of the intestinal flora / gut microbiotaThe intestinal flora / gut microbiota, also called microbiome, refers to the community of microorganisms that live in the digestive tract. A healthy intestinal flora / gut microbiota is crucial for digestion, the immune system, and the overall health of dogs and cats. and improve mucosal health, which can reduce the risk of gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. bleeding and thus of tarry stool.